Stack gas scrubber

ABSTRACT

For reducing air pollution from a cupola stack or any other stack that delivers particulate matter into the atmosphere, a cyclone scrubber is mounted on top of the stack. This includes a ring of circumferentially spaced hollow vanes, each having a leading inner edge and a trailing outer edge. The tops of the vanes and the top of the space encircled by them are covered by a cap that projects outwardly beyond the vanes. A baffle wall encircling the vanes extends downwardly below them from the outer edge of the cap. Spaced below this wall is a bottom wall that extends outwardly beyond the baffle wall to a side wall that extends upwardly. The inner edge of each of the vanes is provided with a pair of nozzles directed laterally in opposite directions for delivering air under pressure laterally into the slots between the vanes and directing it outwardly through the slots. All of the vanes are inclined laterally in the same direction to cause the air issuing from the slots to flow around the inner surface of the baffle wall. Water is sprayed into the slots between the vanes to mix with the air in those slots. Dirt-laden water is separated from the cupola gases by the cyclone action of the scrubber.

United States Patent [191 Moran [451 Nov. 2%, W73

[54] STACK GAS SCRUBBER [76] Inventor: Kevin E. Moran, Longwood Ave.,

Cumberland, Md. 21502 221' Filed: Mar-.24, 11972 [21 Appl.No.:237 860 [52] US. Cl 55/238, 55/282, 55/393, 110/119, 261/79 A [51] lint. Cl. Btlld 45/10 [58] Field ofSearch ..55/235239,242,261.282, 55/263, 393, 257; 261/79 A; 110/119 3,526,082 9/1970 Thuillier 55/235 Primary Examiner-Frank W. Lutter Assistant Examiner-William Cuchlinski, Jr. 7

AttorneyThomas H. Murray et a1.

57 ABSTRACT For reducing air pollution from a cupola stack or any other stack that delivers particulate matter into the atmosphere, a cyclone scrubber is mounted on top of the stack. This includes a ring of circumferentially spaced hollow vanes, each having a leading inner edge and a trailing outer edge. The tops of the vanes and the top of the space encircled by them are covered by a cap that projects outwardly beyond the vanes. A baffle Wall encircling the vanes extends downwardly below them from the outer edge of the cap. Spaced below this wall is a bottom wall that extends outwardly beyond the battle wall to a side wall that extends upwardly. The inner edge of each of the vanes is provided with a pair of nozzles directed laterally in opposite directions for delivering air under pressure laterally into the slots between the vanes and directing it outwardly through the slots. All of the vanes are inclined laterally in the same direction to cause the air issuing from the slots to flow around the inner surface of the baffle wall. Water is sprayed into the slots between the vanes to mix with the air in those slots. Dirtladen water is separated from the cupola gases by the cyclone action of the scrubber.

9 Claims, 5 Drawing Figures H O or Steam STACK GAS SCRUBBER It is among the objects of this invention to provide a cyclone scrubber which can be mounted on top of a eupola stack or the like, which is compact, which is relatively inexpensive, which is efficient and which is easy to maintain.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is a side view of a cupola stack equipped with my gas scrubbing apparatus;

FIG. 2 is an enlarged fragmentary vertical section through the scrubber;

FIG. 3 is a horizontal section taken on the line III-III of FIG. 2; 7

FIG. 4 is a further enlarged horizontal section through a hollow vane; and

FIG. 5 is a vertical section taken on the line V V of FIG. 4.

Referring to the drawings, a ring is mounted on and encircles the top of a cupola stack 1 or other gas emitting stack. As shown in FIGS. 2 and 3, the ring includes an annular plate 2 resting on top of the stack and extending outwardly away from it, and an annular chamber 3 suspended from it around the upper end of the stack. A bottom wall 4 extends outwardly from the bottom of the chamber and supports at its outer edge an upwardly extending outer side wall 5 that encircles the rrng.

Mounted on the ring; that is, on plate 2, is a plurality of circumferentially spaced hollow vanes7 that have their leading edges adjacent the inner edge of the ring and their trailing outer edges adjacent its outer edge. Resting on top of the vanes and also covering the top of the space encircled by them is a cap 8 that includes a small annular chamber 9 inwardly of and above the inner ends of the vanes. The cap extends outwardly beyond the vanes and its outer edge supports a cylindrical baffle wall 10 that extends downwardly to a point below the vanes. This baffle wall is spaced from both the outer side wall 5 and the vanes, and its lower edge is spaced from bottom wall 4. Consequently, the stack gases are compelled by the cap to flow laterally out between the vanes and then down the inner surface of the baffle wall, out beneath its lower edge and then upwardly between that wall and the outer side wall to the atmosphere. By extending the outer side wall up above the level of the cap and securing to its upper edge an inwardly extending, but relatively narrow, top wall 11 the clean gases are directed inwardly again before they escape from the top of the scrubber.

The inner edge of each of the vanes is provided with a pair of nozzles directed laterally in opposite directions as shown in FIGS. 4 and 5. Preferably, these nozzles take the form of parallel vertical slits 13. One way of forming them is to provide the inner end of each vane with a vertical slot, in which a pair of angle bars 14 are placed with their outer flanges extending away from each other. The bars are spaced apart by upper and lower flanged sleeves 15, through which screws 16 extend. Other sleeves 17 are mounted on the outer portions of the screws to space the opposite edges of a vertical deflector strip 18 from the angle bars to form the slits 13. The screws extend through this strip and their inner ends are threaded in clips 19 that engage the inside of the vane at opposite sides of its slots.

Air is delivered under pressure to the inside of the hollow vanes, from which it escapes laterally through the nozzle slits that are positioned to direct it outward through the spaces or slots between the vanes to create an ejector action for the stack gases. This air also keeps the vanes clean and from over-heating when the stack gases are very hot. All of the vanes are turned or inclined laterally. in the same direction to cause the air and gases issuing from the outer ends of the slots between them to produce a cyclone sweeping around the inner surface of baffle wall 10 before the air and gases escape beneath the lower edge of that wall. Most suitably, the vanes taper in section toward their outer edges, and for best results are of air foil shape and curved in the direction of the tangential flow of air around the inside of the baffle wall. The size of the central opening in top wall 11 determines the back pressure and controls the cyclone action. A small opening chokes the flow out of the scrubber and increases the angular acceleration in the cyclone area.

To receive the air for the vane nozzles, the bottom of each vane is open and surrounds an air outlet 21 in the top of chamber 3 below it. Air is delivered under pressure to this chamber through a conduit 22 from a blower 23. Since it may be desirable to adjust the angle of the vanes by swinging their outer edges laterally one way or the other to vary the cyclone effect and to change the throat area that determines the level of scrubbing energy expended on the gases going through the inner ends of the vanes are pivotally mounted on vertical axes. This may be done by means of threaded studs 24 secured to plate 2 and extending up through the tops of the vanes and through the cap above them. Nuts 25 are screwed on the upper ends of the studs.

Another feature of the invention is that water or steam can be sprayed into the air and stack gases flowing outwardly between the vanes. This is accomplished by securing vertical tubes 27 to plate 2 and the overlyingcap, with the upper ends of the tubes opening into the bottom of annular chamber 9. There is one tube between the inner end of each vane and the inner edge of plate 2. These tubes are provided with outlet openings, either a line of orifices or a continuous slit 2%, directed into the slots between the vanes. Water is supplied under pressure from a pipe 29 to chamber 9 to feed the tubes. The water sprays capture the particulate matter in the stack gases, and the moist gas stream swirls around the inside of the baffle wall where the water droplets and solid particles are forced to the outside and fall from the baffle wall into the space below it. From here the dirty water is drained through a pipe 30 into a settling tank 31, from which the sludge can be discharged. The clean water, plus make-up water, is pumped back to the scrubber through a pipe 32.

Since the stack gases might overheat the portion of cap 8 directly above the top of the stack, it is best to provide the cap with a water jacket to help cool it. This can be done by mounting such a jacket 34 on top of the cap and connecting the outlet of pipe 30 and the inlet of pipe 29 to it so that the water from the separating tank on its way to the spray tubes will flow through the water jacket.

Air alone can be used for operating this scrubber to produce the ejector and cyclone actions, or water or steam alone can be used for the same purpose. Usually, however, both will be used together in the proper ratios to produce the best centrifugal separating while conserving water. This scrubber is simple to install and can be operated with variable air power. The high fluid velocity between the vanes produces good mixing of the fluid with the stack gases, which emerge from between the vanes uniformly all around the scrubber and not just at one point.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A stack gas scrubber comprising a ring adapted to be mounted on top of a stack and to extend radially outward therefrom, a plurality of circumferentially spaced hollow vanes mounted on said ring, the vanes having leading inner edges adjacent the inner edge of said ring and trailing outer edges adjacent the outer edge of the ring, a cap covering the tops of the vanes and the top of the space encircled by them and projecting outwardly beyond the vanes, whereby stack gases must flow out through the slots between the vanes, a baffle wall encircling the vanes and spaced outwardly from them, said wall extending downwardly from said cap to a point below the vanes, a bottom wall extending from said ring outwardly beyond said baffle wall and spaced below it, an outer side wall encircling said baffle wall and spaced outwardly from it, said side wall extending upwardly from said bottom wall, means for deliver-ing air under pressure to the insides of the hollow vanes, the inner edge of each of the vanes being provided with nozzle means directed laterally in opposite directions for escape of pressurized air laterally through said nozzle means into the slots between the vanes, all of the vanes being inclined laterally in the same direction to cause the air and stack gases issuing from the outer ends of said slots to flow in a circular direction around the inner surface of said baffle wall, and

means mounted adjacent the inner edges of the vanes for spraying water into the slots between the vanes to mix with the air and stack gases in those slots.

2. A stack gas scrubber according to claim 1, in which said outer side wall extends above the level of said cap, and the scrubber includes an annular top wall extending inwardly from the top of said side wall.

3. A stack gas scrubber according to claim 1, including a water jacket formed on top of said cap above said space, and means for circulating cooling water through said jacket.

4. A stack gas scrubber according to claim 3, in which said water-spraying means include a vertical pipe mounted at the inner edge of each vane and provided with an outlet directed into the slot between that vane and a vane beside it, and a conduit connecting the inside of the water jacket with the upper ends of said pipes.

5. A stack gas scrubber according to claim 1, including means pivotally mounting the inner ends of the vanes on vertical axes to permit their outer edges to be swung laterally to different positions.

6. A stack gas scrubber according to claim 1, in which said ring and the bottoms of the hollow vanes are provided with openings through which said air is delivered to the insides of the vanes.

7. A stack gas scrubber according to claim 1, in which said air nozzle means are formed by vertical slits.

8. A stack gas scrubber according to claim 1, in which said vanes have an air foil shape curved in the direction of said air flow.

9. A stack gas scrubber according to claim 1, in which said water-spraying means include a vertical pipe mounted at the inner edge of each vane and provided with an outlet directed into the slot between that vane and a vane beside it. 

1. A stack gas scrubber comprising a ring adapted to be mounted on top of a stack and to extend radially outward therefrom, a plurality of circumferentially spaced hollow vanes mounted on said ring, the vanes having leading inner edges adjacent the inner edge of said ring and trailing outer edges adjacent the outer edge of the ring, a cap covering the tops of the vanes and the top of the space encircled by them and projecting outwardly beyond the vanes, whereby stack gases must flow out through the slots between the vanes, a baffle wall encircling the vanes and spaced outwardly from them, said wall extending downwardly from said cap to a point below the vanes, a bottom wall extending from said ring outwardly beyond said baffle wall and spaced below it, an outer side wall encircling said baffle wall and spaced outwardly from it, said side wall extending upwardly from said bottom wall, means for delivering air under pressure to the insides of the hollow vanes, the inner edge of each of the vanes being provided with nozzle means directed laterally in opposite directions for escape of pressurized air laterally through said nozzle means into the slots between the vanes, all of the vanes being inclined laterally in the same direction to cause the air and stack gases issuing from the outer ends of said slots to flow in a circular direction around the inner surface of said baffle wall, and means mounted adjacent the inner edges of the vanes for spraying water into the slots between the vanes to mix with the air and stack gases in those slots.
 2. A stack gas scrubber according to claim 1, in which said outer side wall extends above the level of said cap, and the scrubber includes an annular top wall extending inwardly from the top of said side wall.
 3. A stack gas scrubber according to claim 1, including a water jacket formed on top of said cap above said space, and means for circulating cooling water through said jacket.
 4. A stack gas scrubber according to claim 3, in which said water-spraying means include a vertical pipe mounted at the inner edge of each vane and provided with an outlet directed into the slot between that vane and a vane beside it, and a conduit connecting the inside of the water jacket with the upper ends of said pipes.
 5. A stack gas scrubber according to claim 1, including means pivotally mounting the inner ends of the vanes on vertical axes to permit their outer edges to be swung laterally to different positions.
 6. A stack gas scrubber according to claim 1, in which said ring and the bottoms of the hollow vanes are provided with openings through which said air is delivered to the insides of the vanes.
 7. A stack gas scrubber according to claim 1, in which said air nozzle means are formed by vertical slits.
 8. A stack gas scrubbEr according to claim 1, in which said vanes have an air foil shape curved in the direction of said air flow.
 9. A stack gas scrubber according to claim 1, in which said water-spraying means include a vertical pipe mounted at the inner edge of each vane and provided with an outlet directed into the slot between that vane and a vane beside it. 